geaham



(No Model.)

J. GRAHAM, I TELEPHONE TRANSMITTER.

Patentied Apr. 17, .1888,v

INVENTOR:

WITNESSES la'mm Y ATTORNEYS.

' N. PETERi-Phmwmmgraphun Wnhinglonzhl;

'- UNITED, STATES JOHN M. GRAHAM, on PITTSBURG, PENNSYLVANIA, Assrenos'roHiM SELF, SARAH o. GRAHAM, MARTHA GRAHAM, AND rHoMAs o. L.

GRAHAM, ALL OF SAME PLACE.

TELEPHONE-TRANSMITTER.

SPECIFICATION, forming part of Letters Patent No. 381,234, datdApril 17, 1888,

Application filed May 12, 1887.

To all whom it hwy concern.-

Be it known that I, JOHN M. GRAHAM, of P1ttsburg,in the county of Allegheny and State of Pennsylvania, have invented a new and Imwith the diaphragm of a transmitting-telephone, of two pairs of contact-springs arranged to press opposite ends of electrodes carried by springs bearing on the diaphragm,onecontactspring of each pair being. connected with one terminal of the induction-coil, the electrodes operated by the diaphragm being connected with the terminals of the local battery.

In the casing A, provided with the usual mouth-piece, B, is clamped the diaphragm D,

and to the inner walls of the casing A are secured two angled springs, E E, by the screws of the binding-posts a c. The springs EE are inclined toward the center of the diaphragm D,where they are bent outward away from the diaphragm parallel with each other and at right angles to the diaphragm, and upon the extremities of the springs are formed sockets b b for receiving the electrodes, which in the. present case consist of carbon rods 0 0C, .The springs E are insulated from the diaphragm.

'To the casing A are secured four contactsprings, F F, G G. The contact-spring F is offset at its extremity and is provided with a shallow cavity for receiving the outer end of the carbon rod 0.. The contactspringFQwhich is of the same construction,is arranged to bear upon the outer end of the carbon rod 0. The contact'spring G is offset and provided with a shallow cavity for receiving the inner end of the carbon rod 0, and the contact'spring G",

Serial No. 233,014. (No model.)

I which is of the same construction as the spring 0 G,isarranged tobear upon the inner end, of p the carbon rod 0. The contact-springs. F G are connected bya curved plate, H, providedwith arms d, which extend over the contactsprings F G and are provided with adjusting 5 screws e,which bear upon the backsof the contact-springs and serve to adjust their pressure In a v upon the ends of the carbon rods, 0 0, similar manner the contactsprings F G are connected ,by the curved plate H, which is '6o .provided with armsd,having adj ustin'g-screws e". The springs E. E are adjusted by screws f f, passing through arms'g, projecting inwardly from the walls of the casingA over the said springs. i d

In Fig. 1 the arms dd 9 areomitted for the H sake of clearness.

The binding-posts a a are connected with the terminals'of the local battery J. The con- 1. tact-springs F G are connected through the plateH with one terminal of the primary-wire of the induction-coil K, and the contact-springs F G are connected through the curved plate Hwith the remaining terminalof the primary wire of the induction-coil. The terminals of 7 5 the secondary wire are connected with the line and ground in the usual way. 1

When the diaphragm D is set in vibration by sound-waves made in the mouth-piece B,

the inward movement of the diaphragm pushes I the s'pringsE. E backward, d-iminishingthe pressure between the contact-springs G G: and v carbon rodsc c and increasing the pressure 1 between the said carbon rods and the contact-- springs F F, thereby causing the current to I flow from thebattery -J through the springs E E, carbon rods 0 c, and contact-springs F in one direction through the primary wire of the induction-coil. -When the diaphragm retracts, the springs E E follow it and carry the carbon j rods 0 cin the opposite direction, diminishing the 'contactbetween the said carbon rods and the springs -F F and increasing the-contact 1 between the said carbon rods and the springs G G, causing the current to flow in theopposite direction through the primary wire of the induction-coil. I By these two variations of the 1 current the maximum'efiect of induction is produced in the secondary wire of the inductron-coil and strong impulses are sent over the line, which aflect the receiving telephone. When the diaphragm D is at rest,the current flowing to the induction-coil from the battery equally in opposite directions produces no effeet In the coil,and does not therefore interfere with the current sent through the line and and then bent vupwardly and away from the said diaphragm and carrying electrodes at their free ends,and two pairs of contact-springs arranged opposite each other and engaging the ends of the electrodes,the said springs being connected with opposite terminals of the primary wire of the induction-coil, substantially as described.

2. The combination, in a transmitting-telephone, of the casing A, provided with the mouth-piece B, the diaphragm D, clamped in the casing, the springs E E, bearing upon the diaphragm and carrying electrodes 0 c, the contact-springs F G, connected together and with one terminal of the primary wire of the inductioncoil, the contact-spring G being arranged to press upon the inner end of the electrode 0, the contact-spring F being arranged to press upon the outer end of the electrode 0, the contact-springs F G, connected together and with the remaining terminal ofthe primary wire of the inductioneoil, the contact-spring G being arranged to press upon the inner end of the electrode 0, the contact-spring F being arranged to press upon the outer end of the electrode a, and the battery and line connections, substantially as described.

3. The combination, in a transmitting-telephone, of the casing A, provided with the mouth-piece B, the diaphragm D, clamped in the casing, the springs E E, bearing upon the diaphragm and carrying electrodes 0 c, the contact-springs F G, connected together and with one terminal of the primary wire of the induction-coil, the contact-spring G being arranged to press upon the inner end of the electrode c, the contact-spring F being arranged to press upon the outer end of the electrode 0,

the contact-springs F G, connected together and with the remaining terminal of the primary wire of the induction-coil, the contact-spring G being arranged to press upon the inner end of the electrode a, the contact-spring F being arranged to press upon the outer end of the electrode 0, the battery and line connections, and the adjusting-screws e e f f, substantially as described.

JOHN M. GRAHAM.

Witnesses:

KATE SULLIVAN, ANNIE OoNNoLLY. 

